Datasheet

207
6120F–ATARM–03-Oct-06
AT91SAM7X512/256/128 Preliminary
Figure 26-4. Start Bit Detection
Figure 26-5. Character Reception
26.4.2.3 Receiver Ready
When a complete character is received, it is transferred to the DBGU_RHR and the RXRDY sta-
tus bit in DBGU_SR (Status Register) is set. The bit RXRDY is automatically cleared when the
receive holding register DBGU_RHR is read.
Figure 26-6. Receiver Ready
26.4.2.4 Receiver Overrun
If DBGU_RHR has not been read by the software (or the Peripheral Data Controller) since the
last transfer, the RXRDY bit is still set and a new character is received, the OVRE status bit in
DBGU_SR is set. OVRE is cleared when the software writes the control register DBGU_CR with
the bit RSTSTA (Reset Status) at 1.
Figure 26-7. Receiver Overrun
Sampling Clock
DRXD
True Start
Detection
D0
Baud Rate
Clock
D0 D1 D2 D3 D4 D5 D6 D7
DRXD
True Start Detection
Sampling
Parity Bit
Stop Bit
Example: 8-bit, parity enabled 1 stop
1 bit
period
0.5 bit
period
D0 D1 D2 D3 D4 D5 D6 D7 PS
S
D0 D1 D2 D3 D4 D5 D6 D7 P
DRXD
Read DBGU_RHR
RXRDY
D0 D1 D2 D3 D4 D5 D6 D7 PS
S
D0 D1 D2 D3 D4 D5 D6 D7 P
DRXD
RSTSTA
RXRDY
OVRE
stop
stop